It's a known issue. I have not figured out how to fix it yet, but am looking into it. It happens when a story gets moderated out and people have hotlisted it.
ADMIN
I had created a topic about hydrogen fuel cells, but then the post was deleted or something. I already had it added to my hotlist. Now I have this blank thing on my hotlist, that there is no text or link, but still says "comments - 0 new" that I cant make go away. How can I get rid of that?